The invention relates to a method and apparatus for inspecting tubing. More specifically, the invention relates to the use of radiography for nondestructively inspecting tubes in a nuclear steam generator.
From time to time during the life of a nuclear steam generator, it may be desirable to nondestructively inspect portions of the many fluid conducting heat exchanger tubes which comprise a major part of the generator. Because of the closely packed arrangement of the tubes in the steam generator tube bundle and the general inaccessibility of the tube exteriors, the inspections are generally conducted from within a tube. Such inspection techniques have heretofore typically relied on ultrasonic and/or eddy current techniques to detect and generally identify pitting, cracking, and/or erosion of, and/or crud buildup on the tube. While these techniques have been quite useful in generally locating such aberrations, they have been unable to provide some of the information desired about the aberrations. More specifically, it may be desirable to know precisely the orientation shape and definition of cracks and the like in the tube walls. Such information is useful in evaluating the seriousness of the problem and may be useful analytically in establishing the nature, and thus possibly the cause, of the aberration, as well as its degree of severity.